From June 1, all registered foreign nationals who reside in Korea on long-term visas must apply for a re-entry permit before leaving the country if they wish to maintain their status and period of stay. They can do so at their local immigration office (including at the airports).
Please note that leaving Korea without a re-entry permit will result in cancellation of one’s alien registration. Also, all registered foreign nationals granted a re-entry permit must undergo a medical examination for COVID-19 symptoms within 48 hours prior to their return to Korea and carry and present a medical certificate with the results written in English or Korean.